Energy

Energy is an essential part of our daily life. We are highly dependent on energy to keep our societies running. Not only does it enhance quality of life of individuals, it also provides the necessary foundation for technology development for the betterment of lives. Currently, our main source of energy comes from fossil fuels. In face of the blooming world population, the demand for energy is ever increasing. The scarce nature of these non-renewable resources, however, urges the need of long-term solutions to the foreseeable energy crises. The gradually exhausting non-renewable resources, such as coal and petroleum, alone are no longer sufficient to meet such an enormous need. New directions and innovations are needed to cast us a way-out.

Energy storage

To tackle the energy crisis, researchers have developed many ways to extract renewable energy from Nature, such as solar energy, geothermal energy, and tidal energy. Nevertheless, many sources of renewable energy share the same problem that energy generated cannot be stored easily, and people have no control over when they wish to use it. For example, the use of solar energy is limited to daytime only. In fact, energy storage is also essential to non-renewable energy, as it ensures that no energy is wasted when the energy demand is less than the supply. Chemists, therefore, are devising new methods for energy storage in form of chemical energy.

Recent research directions

Solid-state lithium battery link

Looking for safer lithium-ion batteries with higher energy density, intensive research is ongoing to develop solid-state batteries. A solid electrolyte can act as a separator between the cathode and the anode, and hence allow the use of energy-dense anode materials as it is much less likely for the electrodes to have direct contact accidentally.

Rechargeable zinc-manganese battery link
Researchers improved the zinc-manganese battery by separating the electrodes and electrolytes into three chambers with ion-exchange membranes. In this version of zinc-manganese cell, potassium sulfate as the electrolyte is placed in the middle chamber to separate zinc electrode immersing in potassium hydroxide solution from manganese dioxide immersing in a solution of sulphuric acid and manganese sulfate. With this advancement, a two-fold increase and a three-fold increase were recorded for voltage and energy density respectively. Furthermore, this cell is rechargeable.

New electrochemical batteries link1 link2

With the advancements in material science, more and more novel materials are put to test for the ability to make better batteries, including graphene and its derivatives and boron-nitride. Graphene, being an excellent electrical conductor, is also light-weighted and durable. On the other hand, boron-nitride has a tuneable bandgap by doping and introducing defects and is resistant to heat and force.

Thermochemical energy storage link

Thermochemical energy storage systems make use of chemical reactions which release heat or absorb heat. The reported heat battery is composed of a salt and water. When heat is applied, the hydrated salt will be dehydrated, giving you back the salt and water. The heat is then stored and will be released when the salt is hydrated again.

Hydrogen storage link

Hydrogen by itself is a clean fuel as only water is produced. It releases a great amount of energy when combusted or used as fuel in fuel cells. However, the storage of hydrogen in a safe and inexpensive way remains a challenge. Some promising candidates of liquid organic hydrogen carriers are reported in this article.

Energy harvesting

The global energy demand has been increasing exponentially over the decades. However, the supply of fossil fuels is limited. Therefore, there is an urgent need to search for more sustainable energy sources and ways to improve energy production and usage efficiency. In this aspect, chemists not only help to design and build more efficient energy harvesting systems but also propose innovative ways to extract energy from waste. For instance, designing solar cells with higher quantum efficiency.

Recent research directions

Perovskite solar cells link1 link2

Perovskite solar cells are classified as third-generation photovoltaic cells. It has a much wider light absorption range over conventional silicon solar cells and thus achieving higher power conversion efficiency. The power conversion further improves when different perovskites are used in tandem. Ongoing research focuses on developing better perovskite/perovskite tandem solar cells and perovskite/silicon tandem solar cells to push the power conversion efficiency beyond the limits.

Harvesting energy from salinity gradient link

Electricity can be harvested when ions pass through a semi-permeable membrane, creating a potential difference across the membrane. However, this technique is not scalable until researchers reported a MXene-based membrane because the pores can be easily blocked by bacteria or impurities in the solution. Mxene membranes are less expensive, more physically and chemically durable, easy to fabricate, and perform as well as polymeric membranes used conventionally.

Nuclear waste transforms biodiesel waste into useful products link

Upon irradiation of ionizing radiation from nuclear waste, researchers reported that glycerol, which is a by-product in the production of biodiesel, can be converted into solketal and acetol through radical-initiated mechanisms. While solketal can be used as a fuel additive and acetol is a useful feedstock, glycerol has limited uses. Researchers hypothesized that by making use of the radiation produced by spent nuclear fuel, up to 104 tons of solketal could be produced each year, saving much energy.

Phosphorene nanoribbons in perovskite solar cell link

Researchers in the UK have found out that using phosphorene nanoribbons which were discovered just 3 years ago could enhance the performance of perovskite solar cells. The addition of phosphorene nanoribbons provides a favourable energy alignment between the layers, allowing a more effective avenue for hole extraction.